Touchscreens and other touch interfaces allowing users to provide touch inputs have become widely implemented in avionics. For example, single-touch touchscreen interfaces have been successfully implemented in multiple avionic systems and aircraft platforms. Single-touch touchscreen interfaces recognize relatively simple inputs from single-touch gestures such as clicking a button or key, moving a cursor to the location of the touch, switching between windows, or other relative simple single-touch inputs and gestures. More complex single-touch interfaces allow users to long-press, scroll, drag-and-drop. Recent advances in touchscreen technology introduced multi-touch interfaces to avionics. Multi-touch touch interfaces recognize the presence of two, three, or more points on the contact surface of the touch and allow for relatively complex user inputs such as pinch-and-zoom, rotate, tilt, pan, drag-and drop, or other complex multi-touch inputs.
A problem unique to avionics implementations of touch interfaces is caused by the fact that both the touch interface and the user may be subjected to significant acceleration forces in all three axes (e.g., X, Y, and Z) during normal avionics operations. For example, turbulence, rapid maneuvering, landings, takeoffs, sharp turns, evasive maneuvers, or other acceleration events exert large, quickly changing, and sometimes sudden acceleration forces on the user and the touch interface during user input to the touch interface. These acceleration forces can cause inputs to be misinterpreted by the avionics systems, or may cause correct inputs to not be received by avionics systems for both single-touch and multi-touch touch gestures. For example, a user may move a finger laterally or randomly while providing input without intending to do so due to acceleration forces. A simple single-touch input may inadvertently be interpreted by the touch interface as a slide due to X, Y, or Z movement of the aircraft platform. In some cases, a single-touch or multi-touch gesture may be inadvertently done as a result of any combination of XY, YZ, or XZ acceleration forces on the user of touch interface during the initial touch of the touch interface. Further, a drag input may be disrupted, or a single click may be inadvertently applied as a double or triple click in some cases.
It would be advantageous to provide a touch interface system and method to distinguish between a purposeful single-touch or multi-touch input and an input that is inadvertent or that has been altered due to acceleration forces so as to minimize touch interface errors.